1. Field of the Invention
This disclosure generally relates to evaluation systems, and more particularly to systems that evaluate characteristics of an object using electromagnetic energy.
2. Description of the Related Art
There are a number of proposed systems that employ spectral analysis of light received from a sample to recognize the sample.
US Patent Application Publication 2006-0161788 A1 describes full color spectrum object authentication methods and systems. In particular, a spectrum measuring device measures a region of respective sampled objects to produce spectral content information that identifies the sampled objects. The spectrum measuring device includes a plurality of individual sensors, which preferably includes specialized narrow band near-infrared and near-ultraviolet sensors, for example photodiodes or photomultipliers. Computers employ spectral analysis software to generate a unique measured pattern, which is then compared with reference patterns stored in a database. The spectral analysis software may be remotely located on a server accessible by the computers. The spectral analysis is preferably performed using XYZ color space modeling, although other color space models may be employed. The region being sampled may be varied to prevent third parties from easily anticipating the location. Samples may be taken from multiple regions to insure accuracy.
U.S. Pat. No. 5,844,680 is directed to a device and process for measuring and analyzing spectral radiation, in particular for measuring and analyzing color characteristics. In particular, a number of radiation sources are provided in combination with a sensor for detecting radiation within a desired wavelength range. The radiation sources have spectral characteristics that are linearly independent from one another, but overlap so that in combination, the radiation sources generate radiation over the entire desired wavelength range. Alternatively, a single radiation source is provided that generates radiation over the entire desired wavelength range, in combination with a plurality of sensors that have spectral sensing characteristics that are linearly independent from one another, but overlap the entire desired wavelength range. A control unit stores a number of calibration functions with linearly independent spectral characteristics.
The patents and other publications directed to the field of object authentication and/or object identification are too numerous to describe. The above described publication and patent are only representative.